In dentistry, there is a need for replacing missing teeth by an attractive and aesthetic prosthesis. To satisfy this need, an artificial dental root made of tissue-friendly material has been developed. The artificial dental root is implanted into the jaw bone in order to keep the artificial tooth or teeth firmly in position. In most cases, the material of the implant is pure, unalloyed titanium. The artificial tooth or the set of teeth is screwed to the dental implant through a screw channel. In the prior art, the insertion direction of the screw and the screwing direction were the same, consequently the bore-hole passed through the outer, visible surface of the tooth. This made covering of the screw channel rather difficult. Therefore, a dental system is required in which the opening of the screw inserting channel is formed on a non-visible surface.
Patent application EP2289461A1, titled “Dental System,” describes a dental superstructure in which a screw member is inserted into an aperture of a screw channel and a screw member seat with a second aperture for providing support to the head of the screw member during fixation of the dental superstructure to a spacer element or an implant through the second aperture. At least one part of a center line of the screw channel and a center line of the second aperture do not coincide.
In this “Dental System” solution, forming the channel is rather complicated. On the one hand, insertion of the screw is complicated because of the varying diameter of the channel, and on the other hand, the dental superstructure is unreasonably weakened.
U.S. Pat. No. 5,116,225 describes an angulated abutment system for affixing a dental prosthesis to an anchor implanted in the jaw bone. The dental prosthesis can be mounted axially offset from the axis of the implant. Two components of the abutment system allow the dental prosthesis to be adjusted in small angles of rotation.
This solution also takes measures to fix the superstructure from its side facing the oral cavity, but it uses a number of components, the production of which is complicated. Although the channel is formed to be straight, providing an opening from the direction of the dental implant is complicated because of the many intermediate component parts.
Patent application WO 2008/138852 describes an adapter for a dental implant with a conical connection recess in its upper part. The adapter comprises a threaded part for connection with the dental implant and a conical main body corresponding to a conical connection recess of the implant, a tool grip portion allowing for attachment of the adapter to the implant by using a tool, and a connection recess adapted for connection to a spacer element or a dental superstructure.
In the above solution, the spacer is provided with outer and inner threads and on the one hand, it is fixed in the implant, and on the other hand, the superstructure is fixed in it.
Typically, this type of spacer is not used any longer since in recent times superstructures have been screwed directly to the dental implants. For the sake of proper positioning of the superstructure, a suitable interface may be installed between the dental implant and the superstructure.